1. Field of the Invention
This invention relates to aircraft exit door locking systems and, more particularly, to an automatic flight locking system for avoiding inadvertent or deliberate operation of an airplane exit opening means during take-off roll, in-flight, or landing.
2. Background Information
Inadvertent or deliberate opening of an aircraft exit during take-off, in-flight, or during landing can result in severe damage to the aircraft as well as injuries to crew members or passengers. For example, an exit door opened in-flight may be subjected to air and inertial loads that are sufficient to cause door separation and can result in damage from impact of the door with the aircraft structure, ground personnel, or property. Also, opening a door on a pressurized airplane can result in a decompression, thereby resulting in potential harm to passengers and the airplane structure. Of particular concern are doors that are not quickly and easily accessible to cabin crews, such as emergency exits like over-wing hatches and upper-deck canopy doors.
Currently, Federal Aviation Administration (FAA) Advisory Circular (AC) 25.783-1 states that it is not considered acceptable to rely solely on cabin pressure to prevent an inadvertent opening of doors in-flight due to door-opening incidents during unpressurized flight, such as during taxiing and landing. The FAA AC also states that all doors should therefore incorporate features in the locking mechanism that provide positive means for preventing the door from vibrating open or from being opened inadvertently by passengers or crew members. Further, the FAA AC states that this positive means should be effective throughout the approved operating envelope of the aircraft, such as takeoff, flight, and landing, and should not complicate the opening of passenger emergency exits under emergency conditions.
Prior attempts to prevent the inadvertent opening of aircraft exits have monitored air/ground logic and dynamic environmental parameters, such as inertial pitot logic, reference logic, and wheel speed. For example, see U.S. Pat. No. 4,915,326. Such a lock system requires sophisticated sensors and processing capabilities to gather and process the dynamic environmental data in order to perform its locking function. This dynamic environmental data is not readily or easily obtained on older or less sophisticated aircraft.
Thus, there is an unmet need in the art for an automatic flight lock system that avoids inadvertent or deliberate operation of an airplane exit opening means during take-off roll, in-flight, or during landing.